Radio tube tap



Feb. 7, 1939. ALDEN 2,146,612

RADIO T TAP Filed May 11' 1937 lmll INVE OR BY n/ Patented Feb. 7, 1939 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to a socket device or female connector especially adapted to be placed upon the external metal caps with which radio tubes of the so-called screen grid type are provided.

More particularly my invention includes a connector of this type which can be used in connection with differing types of radio tubes, provided with such metal caps or plugs of various dimensions.

One purpose of my invention is to provide a connector for use with screen grid tubes which shall be insulated and prevent the accidental happening of short circuits by contact of other metal bodies therewith, and also to prevent the undesired connection of the operators body to the cap when placing it upon the tube. It has often been found that such caps are removed from tubes or placed upon the same while the tube is in actual operation, as for example when a number of tubes are successively placed in a socket inorder to determine their comparative operating qualities.

When an unins'ulated grid cap is employed under these conditions, there frequently occurs the production of undesirable sounds from the radio receiver, or even the setting up of violent oscillations which may be dangerous to certain portions of the receiver, such as condensers.

Another purpose of my invention is to allow a tap-off to be made from the screen grid circuit of a radio tube without breaking its normal connection to the rest of the radio receiver.

Yet another purpose of this invention is to provide an insulated grid cap for use in connection with so-called tube checkers, where it is desirable that such grid cap be capable of employment with tubes provided with different sized plugs for connection thereto.

Yet another object of this invention is to provide a grid cap in which means are provided so that when the cap is pressed down over the tube plug, the plug will be prevented from entering the cap beyond a certain point, so that the wire connecting to the cap may be firmly soldered to a point in the grid cap which isnot reached by the plug on the tube.

Referring now to the drawing hereunto attached Fig. 1 represents in cross section a double grid cap constructed according to my invention and shown in place over the plug end of a radio tube.

Fig. 2 represents in perspective an exploded view of my double grid cap, illustrating the manner in which the various parts are assembled.

'venient assemblage.

Fig. 3 is a transverse sectional view of the device on the plane of the line 33 of Fig. 1 but without the wire.

My grid cap comprises a body portion Ill, taking the form of a cylinder of large diameter H and a cylinder of relatively smaller diameter I2. These cylinders are concentrically connected with one another so as to form an elongated body.

For the purpose of imparting additional strength to the structure, or of allowing it to fit over a radio tube plug by pressing it still farther upon this plug, I may provide an enlarged collar l3 located at the outer extremity of the larger cylinder. These two cylinders have a partition wall l4 lying therebetween. This wall is pierced by a central aperture l5, which allows the passage therethrough of a hollow eyelet I6. This eyelet is provided with a central passageway IG.

I provide a clip I! of such size as conveniently to fit within the smaller cylinder and another clip l8 of such size as conveniently to fit within the larger cylinder. These clips are preferably constructed of, springy sheet metal, having a generally U-shaped form. The legs of the U in each case are so spaced as to correspond with the diameter of the tube plug over which they are to be inserted and due to the springy nature of the material, each one of these clips will make satisfactory contact with tube plugs having differences of diameter as great as are encountered in practice. Thus, by the employment of two different sized clips, I am enabled to make connection with tube plug structures of a wide range of size. In the assembly of my device, the eyelet i6 is inserted through the aperture IS in clip ll, through the aperture IS in the body dividing wall and through the aperture 20 in clip [8.

Its smaller end may then be headed over by any convenient means, thus serving to form a compact and relatively rigid structure, where both clips have the bridge portions of their respective Us firmly held against the dividing wall M by means of the eyelet l6 which serves to rivet them in place.

For purposes of external connection to my plug cap I provide an aperture 2| located in a lateral portion of one of the cylinders, preferably the larger cylinder for purpose of more con- Through this aperturepasses an insulated conductor 22. This conductor has the insulation removed from its end portion for a sumcient distance so that such bared portion will pass completely through the central passageway of eyelet l6 and may be soldered or otherwise fastened upon the opposite end of this eyelet as indicated at 22'. Likewise I have found it desirable to solder or otherwise fasten this conductor to the eyelet at the point 23 where it enters the passageway of the eyelet. If desirable, for any reason, the entire passageway through the eyelet may be filledwith solder to more securely hold the wire in position. The turning of the wire at the point where it leaves the eyelet, and its passage through aperture 2| serve to relieve the soldered joint from a portion of any strain which may be inserted upon the wire. The internal solderingof this wire may conveniently be done by means of a soldering iron having a relatively small point which can be inserted into the cylinders, constituting the insulating body of this cap. Undue rotation of the clips, which might loosen or break the wire connection, is avoided by providing the body recesses with shoulders 30, which act to confine the rotational motion of the clips to a few degrees, as shown in Fig. 3.

I have found that it is highly desirable for the connecting wire of my cap to be thoroughly insulated to a point extending within the body of the can so that the insulation will not readily be pulled back and expose a portion of bare wire outside the cap, which contingency might allow an accidental short circuiting connection to occur where the wire was thus bared. However it is possible and sometimes preferable for my ingrid tubes having various sized external plugs,

my invention is also susceptible to many other uses. For example, a radio set may be provided with screen grid caps constructed according to' my invention and thus be enabled to employ tubes of different types at will, in a single socket.

In case that it is desired to use my invention as a means of afiording a tap-oi to an existing circuit already derived from the tube plug, one convenient method of so doing is the following.

My grid cap is placed upon the tube plug structure and the connecting wire leaving the side of the cap will afford one circuit connection to this terminal of the tube. In the other end of my cap there may then be placed a conducting plug of sufficient length so that it will project beyond the insulating body of my cap. An additional 'circuit connection may then be made to this secondary projection by any suitable cap device, such as another cap built according to my invention. It can be seen that in this fashion a great number of circuits may be connected to a single tube plug terminal, if so desired, merely by placing a series of my cap devices one on top of the other, with suitable connecting plugs serving to key each cap to the next one, and each cap affording one external connection through its wire conductor.

The end l2" of the device serves as an extension handle to facilitate the use of the device when applying it to a tube tip which fits in the socket l8. Vice versa the end l3 serves as a handle for applying the device to a tip which fits in socket l'l. When only one socket or clip is necessary the device may be closed at the opposite end. While I have referred to the body as "cylindrical" it should be understood that this term is not used in its true geometrical sense as the cross section might be polygonal.

If desired the body and the conductor may be shielded.

I claim:

1. A tube tap having an insulating body with into the hollow rivet so as to minimize the effects of external pulling strain upon said inner portion of said conductor. a

2. A double-ended grid cap in the form of two metallic clips connected to one another at substantially the center points of each clip soas to form a double U-shaped structure, by means of a hollow cylindrical body having an axially extending opening therethrough and being of a diameter small relative to the diameter of said clips, said cylindrical body affording entrance into the axial opening thereof for a connecting wire and said clips and saidv cylindrical body being enclosed by insulating material substantially at all points except the open ends of said clips and at a point affording entrance to said wire.

3. Aninsulated grid cap including a hollow body of insulating material provided with recesses of different sizes at its oposite ends, said recesses having a common bottom, constituting a division wall therebetween, connecting clips fitting into each respective recess, each clip'corresponding in size to its respective holding recess, a hollow rivet passing through said clips and said common division wall so as to hold the clips firmly thereagainst, a connecting wire passing through a lateral wall of said insulating body, bending substantially at right angles and entering said hollow rivet with the portion thereof lying-within said rivet bared and the portion thereof situated at the point of entrance into said insulating body covered with insulation, and means for fastening said wire within said rivet.

4. An insulated grid cap for radio tubes and the like including an insulating body in the form of two cylinders of unequal diameter joined to one another so as to form an elongated body, and having substantially at the point of juncture an insulating disc forming a partition therebe-. tween, said partition being provided with a central aperture therethrough, a first metallic clip of the U-shaped type substantially conforming to the internal diameter of one cylinder, a-second clip of like type and substantially conforming to the internal diameter of the second cylinder, both said clips beingprovided in their respective bridge portions with apertures substantially conforming in size with the central aperture in said partition, and lining up therewith when said clips are inserted in their respective cylinders, a hollow eyelet passing through said apertures in said clips and said partition so as to hold said clips against said partition, at least one of said cylinders being provided near its point of juncture with the other cylinder with a lateral aperture, whereby a connecting wire may be inserted laterally into said cylinder, so as to pass into said hollow eyelet.

5. A double connector including at the respective ends thereof, two clips of difierent diameters, a common mounting memberJying therebetween,

connecting and fastening means passing through said mounting member and holding the bases of said clips upon said mounting member and re spectively opposite one another so as to locate the open ends of said clips substantially 180 apart, said fastening means having a hollow passage extending therethrough longitudinally of the connector, insulating means covering both said clips except the open ends thereof and having a discrete aperture therein afiording a lateral point of entry, a conductor extending through said discrete aperture laterally of the connector and having its innermost portion bent substantially at right angles to its lateral portion, and extending through said fastening means so as to extend axially of the connector.

6. A grid cap including an elongated onepiece insulating body having oppositely disposed recesses with an insulating partition therebetween, said partition having a central aperture therethrough, two metallic U-shaped clips of different sizes, one lying within each recess of said body, each of said clips having an aperture in its respective bridge portion, coaxial with said central aperture of said insulating partition, a fastening member passing through said central aperture and the respective apertures of said clips so as to hold said clips against opposite sides of said insulating partition, said body being provided with a lateral aperture leading to one of said recesses, and a connecting wirepassing through said lateral aperture and having its inner portion mechanically and electrically connected to one of said clips.

MILTON ALDEN. 

